﻿#region Copyright & License

//
// Author: Ian Davis <ian.f.davis@gmail.com> Copyright (c) 2007-2008, Ian Davs
//
// Portions of this software were developed for NUnit. See NOTICE.txt for more
// information. 
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
//

#endregion

#region Using Directives

using System;
using System.Collections;
using Ensurance.Properties;

#endregion

namespace Ensurance.Constraints.Prefix
{
    /// <summary>
    /// SomeItemsConstraint applies another constraint to each item in a
    /// collection, succeeding if any of them succeeds.
    /// </summary>
    public class SomeItemsConstraint<T> : PrefixConstraint<T>
    {
        /// <summary>
        /// Construct a SomeItemsConstraint on top of an existing constraint
        /// </summary>
        /// <param name="itemConstraint"></param>
        public SomeItemsConstraint( Constraint<T> itemConstraint )
            : base( itemConstraint )
        {
        }

        /// <summary>
        /// Apply the item constraint to each item in the collection, failing if
        /// any item fails.
        /// </summary>
        /// <param name="actual">The value to be tested</param>
        /// <returns>True for success, false for failure</returns>
        /// <exception cref="ArgumentException">if actual is not an ICollection</exception>
        public override bool IsSatisfiedBy( T actual )
        {
            Actual = actual;

            PassModifiersToBase();

            if ( !( actual is ICollection ) )
            {
                throw new ArgumentException( Resources.ValueMustBeCollection, "actual" );
            }

            foreach ( object item in (ICollection) actual )
            {
                if ( BaseConstraint.IsSatisfiedBy( (T) item ) )
                {
                    return true;
                }
            }

            return false;
        }

        /// <summary>
        /// Write a description of this constraint to a MessageWriter
        /// </summary>
        /// <param name="writer">The writer on which the description is displayed</param>
        /// <exception cref="ArgumentNullException">if the message writer is null.</exception>
        public override void WriteDescriptionTo( IMessageWriter writer )
        {
            if ( writer == null )
            {
                throw new ArgumentNullException( "writer" );
            }

            writer.WritePredicate( Resources.SomeItem );
            BaseConstraint.WriteDescriptionTo( writer );
        }
    }
}